Table of contents

This paper describes a new angular displacement interferometer based on the internal-reflection effect. In order to make use of the internal-reflection effect, a novel prism assembly is designed, which yields a very compact optical configuration. As a result, the linearity of the angular displacement interferometer is greatly improved. Both the linearization of the measurement equation and the experimental verification of the analysis have been conducted and the results are presented here in detail. The main factors affecting the angle measurement are also addressed. The results of the experimental verification are in good agreement with the theoretical analysis.

The construction and testing of a portable gallium fixed point blackbody are described. The variation of the duration of the melt with thermostat temperature is demonstrated. The stability of the melt and uniformity of the radiance field at the aperture is shown to be better than .

A radiant heating system is described which is capable of raising the temperature of a test specimen to C in approximately 10 s, while the apparatus remains at room temperature. The system uses two infrared lamps which are controlled with an electronic timer to within a resolution of 0.1 s. The radiant heaters reach 90% of their maximum power in approximately 3 s. The radiant heating system has been used to heat tensile specimens prior to impact loading using the tensile split-Hopkinson pressure bar. Impact tensile tests at a nominal strain rate of and initial temperatures of 20, 200, 400 and C were performed on the titanium alloy 90% Ti-6% Al-4% V. A sharp reduction in yield stress and an increase in elongation at fracture were noted in the high-temperature tests. The implicit finite element code ABAQUS has been used to model the radiant heating and thermal diffusion in the tensile specimen and loading bars. The modelling has been used to determine the thermal distribution in the test specimen prior to loading and the validity of the calibration technique.

Magnetic resonance imaging (MRI) requires the use of three sets of coils to produce magnetic field gradients, one for each axis, to encode three-dimensional information. The magnetic field generated by gradient coils has to change as linearly as possible with distance so as to avoid heavy distortion of the resulting image of the sample. The reduction of the dimensions of the magnets for MRI applications has made it necessary to construct gradient coils that can be placed in reduced spaces and, at the same time, provide the uniformity necessary for MRI. A novel cylindrical gradient coil design is described to perform high-resolution imaging of large samples, having a large cylindrical zone of gradient uniformity, co-axial with the coil. This design, referred to as the butterfly coil, produces a magnetic field along the axis of the cylinder and a field gradient in the perpendicular direction (transverse gradient). The butterfly coil design has been simulated and compared, both in homogeneity and efficiency, with a preceding gradient coil geometry. The coil has been constructed and experimental measurements performed. The aspect ratio, defined as the ratio between the length h and diameter d of the cylinder of the coil, is very low. In fact, mathematical simulations and experimental measurements have been carried out on a gradient coil system having . Despite its low-dimensional ratio, this gradient coil system has been proved to be very accurate, both in uniformity and efficiency, in a relatively great volume.

The calibration of vibration pick-ups by the sine-approximation method has been examined. This method which uses a modified Michelson-type laser interferometer has been proposed as an ISO draft standard. The evaluation procedure, the experimental set-up and calculation of the uncertainty in the phase lag are reported. A piezoelectric-type vibration pick-up has been evaluated experimentally. Expanded uncertainties of less than in phase-lag evaluation have been obtained in the experiment.

A simple achromatic retarder made of two plates of different birefringent materials can only be used over a limited range of wavelengths. One way to overcome this limitation is by using a combination of three such achromatic retarders. However, such a combination has the drawback that the orientation of its principal axis varies with the wavelength. An alternative method that is free from this drawback is to use a combination of three plates of different birefringent materials. This paper shows how this method of achromatization can be extended and presents a systematic design procedure for a superachromatic retarder using four plates of different birefringent materials giving an almost constant retardation over a very wide wavelength range.

The state-of-the-art of optical correlation diagnostics of random phase objects is considered both in the framework of conventional notions of the theory of probability and using the concepts of chaotic oscillations theory. A promising fractal approach for the object structure diagnostics is discussed. In particular, the possibility of estimation of the Cantor fractal's dimensions through measurement of a correlation dimension of complexity at the diffracted optical field is shown. This possibility is realized using an original technique for the measurement of a complexity at optical fields.

We have designed and built an optical fibre power detector based on a large-area silicon PIN photodiode and a concave mirror in a wedge-trap configuration. The detector was designed as a high-accuracy transfer standard for near IR (835-865 nm) optical fibre power measurements with multimode fibre-ribbon cables in a manufacturing-production environment. Additional requirements were that the detector be insensitive to the input beam geometry, and able to accommodate different optical fibre connector types, collimated laser light, and highly diverging light from optical fibres. Four identical copies of the detector were evaluated at the NIST Laser Sources and Detectors Group calibration facility and one was tested in the manufacturing environment. The spatial and angular responsivity was highly uniform and varied less than 1% for angles of incidence ranging from to . Absolute spectral responsivity measurements, for collimated and diverging light input wavelengths ranging from 672-852 nm, showed quantum efficiencies as high as 99%. Linearity measurements from a few nanowatts to a few milliwatts indicated a nonlinearity of only 0.05%.

This paper reports an improved thermodynamic method which uses a highly sensitive phase-comparison technique to measure the acoustic nonlinearity parameter . A phase-calibration procedure was introduced. The measurement can be achieved automatically by computer with a program written in HP VEE. Several measurements have been made for distilled water and organic liquids. The experimental results agree well with those in the literature. The inaccuracy of the method is 2.2%.

parameter, phase-comparison technique, speed of sound, pressure, water, organic liquids

An ultrasonic constant-beam-width transducer system which is capable of generating an extended focal zone by electronically focusing the beam over the desired water-depth range is described. Beam directivity measurements show that the higher beam directivity and the reduction in side-lobe level lead to an increase of the signal-to-noise ratio by up to 15 dB compared with that of a plane disc transducer. It also allows one to attain a significant reduction of undesirable spectral broadening effects which in the case of plane disc transducers lower the final resolution and interfere with the correct interpretation of data. Using the focalized transducer, simultaneous 3D velocity component profile measurements over the whole water depth are carried out in uniform, open-channel flow and reveal the presence of coherent structures. In the transversal direction, a stationary secondary current composed of two stationary vortices is observed. Compared with a plane disc transducer system, the focalized system increases the resolution by up to 50%.

In this paper, the semi-empirical laws of King and Jørgensen are adopted as the starting point for modelling the voltage output response of a single normal hot wire. The single fact of having released the King law exponent n in the factor expressing the orientation effects increases significantly the accuracy of the modelling; then the parameter k is only slightly dependent on the orientation of the hot wire in the flow.

We demonstrate a novel analysis that improves the accuracy of angle-dependent elastic-wave velocities in plates for water-immersion measurements. Water-immersion measurements utilize the conversion from longitudinal to transverse mode to determine the velocities of transverse waves. However, beyond the critical angle for longitudinal waves, the phase of the transmitted transverse waves is affected by the presence of evanescent longitudinal waves at the interface. With pulse superposition analysis this effect systematically decreases the apparent velocities at some angles. Previous researchers have corrected the apparent velocities by calculating the theoretical phase shift from known parameters, but this correction requires narrow-band pulses or tone bursts as well as estimations of these parameters. An advantage of our analysis is that it eliminates the need for a priori estimations of parameters. In addition, this analysis allows the use of broad-band pulses that are more applicable to thin plates. To demonstrate these advantages, measurements were conducted on an isotropic steel plate as it was rotated in an immersion tank and insonified with a broad-band ultrasonic transducer. We compared velocities determined by the pulse-echo superposition analysis with velocities determined by our analysis. As expected, there was no significant difference between the longitudinal velocities, but systematic variations in the transverse velocities were lower with this new method.

In this work a technique for the rapid determination of the liquidus and solidus temperatures of oxide systems - in particular titania-rich slags with equivalent contents of 85% and above - was developed. The technique employs a thermocouple to serve the three functions of heating element, sample holder and temperature sensor. Liquidus and solidus temperatures were determined from the cooling curves recorded with this thermocouple. The technique was calibrated against the known binary system and accuracies of C were obtained. FeO and samples melted in atmospheres with different partial oxygen pressures, utilizing the thermocouple configuration of the present study, indicated rapid reaction of the samples with the atmosphere.

A pulsed electro-acoustic system is described which enables electric fields up to to be generated in thin (100-) insulating plaque samples with measurement of the dynamic net space charge density, as a function of temperature and of distance through the thickness of the sample, and the external circuit charging current. From these measurements, the dynamic electric field, potential and conduction current density distributions within low-density polyethene samples have been obtained and are reported.

An application of a mode dielectric resonator is described for precise measurements of complex permittivity and the thermal effects on permittivity for isotropic dielectric materials. The Rayleigh-Ritz technique was employed to find a rigorous relationship between permittivity, resonant frequency, and the dimensions of the resonant structure, with relative computational accuracy of less than . The influence of conductor loss and its temperature dependence was taken into account in the dielectric loss tangent evaluation. Complex permittivities of several materials, including cross-linked polystyrene, polytetrafluoroethylene, and alumina, were measured in the temperature range of 300-400 K. Absolute uncertainties of relative permittivity measurements were estimated to be smaller than 0.2%, limited mainly by uncertainty in the sample dimensions. For properly chosen sample dimensions, materials with dielectric loss tangents in the range of to can be measured using the mode dielectric resonator.

The finite element method has been used for modelling the electrostatic field and for calculation of the capacitance and deviations from ideal behaviour of displacement sensors on the basis of the potential linearity of the versus distance dependence. Various designs of sensors, the effects of electrode roughness, spherical deformation, rounding of edges and tilt have been analysed. The elimination of errors due to fringing of the electrostatic field is most effective with thick electrodes and the gap between the central electrode and the guard ring filled with a dielectric. Any deviation from planarity causes deterioration of the linearity. The most serious sources of error are the tilt and eventual rounding of the working electrode's edge, especially at small electrode separations. If the tilt may change with distance, then the electrodes should be preferentially aligned in their closest position.

The working of the Pichugin pulse generator (named after its Russian inventor) is accurately studied. The influences of inductance and capacitance on the output signal characteristics are studied. A theoretical expression for the output signal's rise time, versus the stage number and the component values, is established. A technical innovation, consisting of an asymmetrical structure which allows an important decrease in rise time and an increase in output peak voltage, is proposed. The realization of a 175 kV, 210 ns rise time, six-stage asymmetrical pulser is proposed and discussed. The improvement compared with the performances of the equivalent symmetrical pulser, for the same rise-time value, is about 50% more voltage.

A very low frequency folded pendulum has been used to measure the horizontal ground displacement at a site near the Indian Ocean. The results show a close correlation between the displacement and ocean wave height. This suggests that such a pendulum can provide a simple land-based wave measurement system and, in an array, can provide tomographic images of the wave height along extended shorelines.

In this paper, we describe a temperature controlled outgassing measurement in the case of electron-beam heating of graphite samples used in divertors of Tokamak-type installations. On the basis of a discrete-time process model in the state space, we developed finite-time settling control of the sample's temperature. We further present the response of closed-loop systems to a unit-step load disturbance and a unit-step reference input.

A system to interface a personal computer to a stylus-type surface roughness measuring instrument has been developed at the National Institute for Standards (NIS). The system has been calibrated and values of the calibration constant (Kcal) have been obtained. Three different types of reference specimens having three different patterns of irregularities were used for the calibration. Repeated measurements of Kcal values were carried out under different calibration conditions. Histograms of the repeated results were developed and the distributions of the results were found to be normal. The repeatability associated with the Kcal values differs significantly. The repeatability error (based on limits) is less than %, although this figure could be improved to be less than % if certain precautions are adopted.

A computer-controlled technique was developed to measure the current-voltage dependences in high- superconductors. The system is based on the multichannel averaging technique. The current through the sample follows a triangular bipolar waveform and is measured by a data acquisition board to be used as an index to a memory array in which the sample voltage is to be averaged. Applying this principle, the noise level present in the sample voltage virtually does not matter. The desired signal will build up, from the noise, proportional to the square root of the number of scans. The main advantage of this technique is the simple and inexpensive hardware requirements.

V dependences, electronic instrumentation, superconductivity research

1998 October 11-16 6th International Conference on Nuclear Microprobe Technology and Applications, Cape Town, South Africa Details: Mrs G Stone, National Accelerator Centre, PO Box 72, Faure 7131, South Africa. Telephone: +27 21 843 3820, fax: +27 21 843 3543, e-mail: icnmta98@nac.ac.za, WWW: http://www.nac.ac.za/icnmta98 19-23 Precision Thermometry Workshops, Gaithersburg, MD, USA Details: Andrea Swiger, National Institute of Standards and Technology, Bldg 221, Rm B1128, Gaithersburg, MD 20899-0001. Telephone: +1 301 975 4800, fax: +1 301 548 0206, e-mail: andrea.swiger@nist.gov December 8-11 2nd Asian Meeting on Ferroelectrics, International (AMF-2), Singapore Details: Weiguang Zhu, fax: +65 792 0415, e-mail: ewzhu@ntuvax.ntu.ac.sg 1999 February 17-18 Sensor and Transducer Conference at mtec '99, National Exhibition Centre, Birmingham, UK Details: Robert Bogue, mtec Conference Chairman, Tamar House, Tuckermarsh, Bere Alston, Devon PL20 7HB, UK. Telephone: +44 1822 840 434, fax: +44 1822 841 300 March 30 March-1 April Symposium on Design, Test and Microfabrication of MEMS/MOEMS, Paris, France Details: B Courtois, telephone: +33 4 7657 4615, fax: +33 4 7647 3814, e-mail: Bernard.Courtois@imag.fr April 13-15 International Workshop on Optical Measurements '99, Liverpool, UK Details: Telephone: +44 151 231 3585, fax: +44 151 709 5057, e-mail: ems@livjm.ac.uk, WWW: http://www.ceorg.livjm.ac.uk/opticalmeas99/ May 17-21 3rd CCM Conference on Pressure Metrology from Ultra High Vacuum to Very High Pressures (10-7 Pa to 109 Pa), Torino, Italy Details: M Bergoglio, Istituto di Metrologia `G Colonnetti', Strada delle Cacce 73, 10135 Torino, Italy. E-mail: bergoglio@imc.to.cnr.it 18-20 Sensor '99 9th International Fair and Congress for Sensors, Transducers and Systems, Nürnberg, Germany Details: ACS Organizations GmbH, PO Box 23 52, D-31506 Wunstorf, Germany. Telephone: +49 5033 2015, fax: +49 5033 1056, e-mail: acs@sensor99.de, WWW: http://www.sensor99.de 20-22 ODIMAP II 2nd Topical Meeting on Optoelectronic Distance/Displacement Measurements and Applications, Pavia, Italy Details: AEI-Ufficio Centrale, P.le R. Morandi 2, 20121 Milano, Italy. Telephone: +39 02 777 90205/218, fax: +39 02 798817, e-mail: conferencesaei@aei.it, WWW: http://ipvsm8.unipv.it/leos or http://www.aei.it/odimap2.html June 7-10 Transducers '99 10th International Conference on Solid State Sensors and Actuators, Sendai, Japan Details: J Etizen, telephone: +81 3 3299 1371, fax: +81 3 3299 1361, e-mail: tr99@twics.com, WWW: http://www.com.cas.uec.ac.jp/trans99.html 13-18 IMEKO XV World Congress, Osaka, Japan Details: c/o The Society of Instrument and Control Engineers, 35-28-303, 1-Chome Hongo, Bunkyo-ku, Tokyo 113. Telephone: +81 3 3814 4121, fax: +81 3 3814 4699, e-mail: mnami@sice.or.jp 21-25 Frontiers and Science and Measurement, National Physical Laboratory, Teddington, UK Details: Jane Tsakalou, telephone: +44 181 943 6400, fax: +44 181 943 6735, e-mail: jane.tsakalou@npl.co.uk, WWW: http://www.npl.co.uk September 12-15 1st International Symposium on Turbulence and Shear Flow Phenomena, Santa Barbara, CA, USA Details: N Kasagi, Department of Mechanical Engineering, University of Tokyo, Tokyo 113 8656, Japan. Telephone: +81 3 3812 2111 ext. 6417, fax: +81 3 5800 6999, e-mail: kasagi@thtlab.t.u-tokyo.ac.jp, WWW: http://tsfp.t.u-tokyo.ac.jp 12-15 EUROSENSORS XIII, The Hague, The Netherlands Details: R F Wolffenbuttel, telephone: +31 15 278 6287, fax: +31 15 278, e-mail: eurosensors@ei.et.tudelft.nl 16-18 September 3rd International Workshop on Particle Image Velocimetry, University of California-Santa Barbara, USA Details: Professor C D Meinhart, Mechanical and Environmental Engineering Department, University of California-Santa Barbara, CA 93106, USA. Telephone: +1 217 333 3752, fax: 217 244 5707, e-mail: piv99@engineering.ucsb.edu, WWW: http://www.engineering.ucsb.edu/~piv99

Although it is 70 years old, there are still areas of quantum theory which are open to interpretation. This book deals with such interpretational problems, and in particular with the issue of the measurement process.

The main theme is whether quantum mechanics can be viewed as a (semantically) complete theory, namely as a theory capable of describing not only the physical object under observation but also the measuring instruments used to detect the properties of that physical object. The problematic aspects arise from the fact that the measuring instruments themselves behave as classical physical systems. Thus, we are faced with the open problem of the transition from the quantum to the classical, or more explicitly, the problem of why the composition of many quantum micro-objects gives rise to classical macro-objects.

This book goes carefully, exhaustively, and deeply into the interpretational problems of quantum mechanics induced by the measurement process. The solution of many relevant issues, as well as the problems that remain unsolved, emerge clearly. The discussion itself is self-contained and the technical parts are reader-friendly.

This book is of value to graduate students and researchers who have an interest in the physical, mathematical, and philosophical foundations of quantum mechanics.

This is an excellent book covering the subject of optical engineering. It is primarily aimed at engineering students and engineers wishing to learn the subject of optical engineering. It is also a book around which courses in optical engineering can be designed and the inclusion of many references, worked examples, and problems make this book especially suitable for this purpose. This book will also be useful to scientists from many disciplines, including optical engineering, wishing to learn more about the area or to use the book as a standard reference.

The book contains chapters covering the principles of reflection and refraction, lenses and aberrations, optical instruments, detectors, spatial light modulators, lasers, linear system transforms, diffraction, interference, holography, signal processing, and fibre optics. These topics are discussed to an appropriate depth for the intended readers of this book. Included within these chapters is a great deal of practical information and worked examples concerning the techniques and devices discussed. The book does not contain other topics from the vast domain of optical engineering, for example, the formation and application of speckle patterns, spectroscopy, fluorescence and other sensing techniques. In fairness to the authors, these subjects are outside the intended scope of this book.

Due to the large breadth of this book it is not intended, and would not be recommended, to be used in isolation. This is not meant to discourage someone wishing to purchase this book, merely as a warning that some of the other texts referenced in this book may need to be referred to at times.

The quality of presentation in this book is generally very high and only one typographic error and omission from the index were noticed. In summary, it is felt that this is an excellent book, and is wholeheartedly recommended.

This admirably readable book provides a clear account of a variety of sensors that are based on ultrasound and used in the process and chemical industries. It is unfortunate that the publishers have truncated the cover title to the rather misleading Ultrasonic Sensors. The author is, in fact, at pains to point out that this is not a book on ultrasonic sensing techniques in general, but only techniques applied in `industrial plant in which fluids are processed, used or stored'.

The book is aimed at practising scientists and engineers who are not specialists in ultrasonics, and a particular strength is the first section, which covers the physics of ultrasound and ultrasonic transducers. In seven chapters, the author provides a comprehensive and interesting introduction to the field that is jargon-free and uses only the minimum mathematics. The chapter on piezoelectric transducers in particular is probably the best general introduction to the subject I've come across.

The treatment does not lack rigour - the appropriate use of references and the comprehensive bibliography are amongst the book's strong points - but the author succeeds in using anecdote and humour to good effect, particularly in this first section.

Part 2 of the book Description of ultrasonic sensors is the heart of the work, but surprisingly, the weakest section. The clarity of style is still evident, the diagrams are well chosen and helpful, and individual sensing techniques are well described. However, the reader is left with a sense that the thematic structure has been lost. Liquid level detection, for instance, is split between chapter 8 Point level detectors (and some continuous level detectors) and chapter 11 Sonar. In between these is a rag-bag chapter 9 ( Sensors where the velocity of ultrasound is determined) and a very good chapter on flow measurement. The titles of chapters 8 and 9 alone demonstrate the author's struggle to impose some logical order on what is a diverse collection of techniques linked only by the use of ultrasound at some point in the measurement process.

The final section consists of six extended appendices, which are logical and well structured. The appendices dealing with acoustic velocity, acoustic attenuation, waveguides, and piezoelectric materials are authoritative and fascinating. Here the author appears to be dealing in more detail with some of his own pet interests; the result is a mine of useful information, concisely presented. A directory of suppliers and bibliography round off the book.

The author's enthusiasm for his subject is apparent throughout this book, as is his ability to explain technically difficult issues in an enlightening and non-mathematical way. It deserves a wide readership.